Paperboard cup with moisture absorbing protection

ABSTRACT

An open-top cup comprises a bottom wall and a side wall having inner and outer surfaces extending upwardly from the bottom wall. An outwardly curled lip formed on the free edge of the side wall. A respective insulative layer having a moisture absorbing characteristic and a respective graphic layer are attached to the outer surface of the side wall. The insulative layer is sandwiched between the outer surface of the side wall and the graphic layer.

RELATED PATENT APPLICATION

This is a non-provisional application which claims priority from U.S. Provisional Patent Application Ser. No. 61/502,048 filed on Jun. 28, 2011.

FIELD OF THE INVENTION

Cups produced from expanded polystyrene (EPS) and cups produced from coated paperboard have long been used in the foodservice business for serving cold beverages. One favored attribute of EPS cups is the insulation properties which minimizes condensation formed on outside surface of the cup as a result of transpiration of atmospheric water vapor. Paper cups have higher thermal conductivity than EPS which results in faster rates of condensation than better insulated cups.

Recent changes in environmental and health concerns around styrene have created a demand for paper cups which show minimal dripping of condensation while containing cold beverages and maintain flexural rigidity as condensation forms and avoid the EPS issues regarding health and disposal. The paper cups provide a smooth surface for high quality graphics and provide an option for industrial composting where such is available. It also provides an opportunity for recycling, and employs a strategy of source reduction to use a minimum amount of material to achieve the objectives. Insulated paper cups, such as the International Paper Hold&Go®, Georgia Pacific Insulair®, and Horhauf wrapped cup, have partially addressed similar concerns for hot beverages. However, the aforementioned cups have limitations in their ability to hold cold beverages while minimizing moisture condensation on the outer surface of the cup and maintaining rigidity during the time it takes to consume a beverage.

SUMMARY OF THE INVENTION

Typical paper cups have an interior coating which provides a water barrier between the beverage and inner paper surface and an exterior plastic layer which provides moisture protection of the paper against condensation, and a graphics surface compatible with industrial printing. This invention provides an outer layer for graphics capability, an insulative layer between the graphics surface and the cup outer surface, an optional absorbent layer for trapping condensation between the graphics layer and the water barrier coating of the cup interior, a flexural rigidity for comfortable gripping, and optionally removes the condensation protection of the exterior of the typical cup.

Accordingly, one aspect of the present invention is directed an open-top cup comprising a bottom wall and a side wall having inner and outer surfaces extending upwardly from the bottom wall and an outwardly curled lip formed on a free edge of the side wall. An insulative layer having a moisture absorbing characteristic is configured to be attached to the outer surface of the side wall coextensively. A graphic layer is configured to be attached to the insulative layer coextensively and wherein the open-top cup has at least 25% higher moisture absorbing capability as compared to an open-top cup without having the insulative layer. The insulative layer is an insulative-absorbtive layer contains fibers which absorb moisture or water. The insulative layer includes 20 to 350 gsm of fibers from the group of cellulose, PLA, bicore PLA-cellulose, starch, and paper. The insulative layer of air laid fibers is made of a layer of cellulose, propylene, or other fibers which is formed into a sheet having a mass density lower than typical paperboard, i.e. less than 11 pounds per 3000 square feet per mil of thickness. The low density of the air laid fibers results in a lower thermal conductivity than a typical paper of equivalent thickness. The graphics layer comprises a printable surface of paper, clay, LDPE, PP, PET or other noncompostable thermoplastic.

Another aspect of the present invention is directed to an open-top cup comprising a bottom wall, a side wall having inner and outer surfaces extending upwardly from the bottom wall and an outwardly curled lip formed on a free edge of the side wall. An insulative layer has a moisture absorbing characteristic that is configured to be attached to the outer surface of the side wall coextensively. The insulative layer includes 20 to 350 gsm of fibers from the group of cellulose, PLA, bicore PLA-cellulose, starch, and paper. A graphic layer is configured to be attached to the insulative layer coextensively and wherein the open-top cup has at least 25% higher moisture absorbing capability as compared to an open-top cup without having the insulative layer and wherein the graphics layer comprising a printable surface of paper, clay, LDPE, PP, PET or other noncompostable thermoplastic.

BRIEF DESCRIPTION OF THE DRAWINGS

A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of an open-top paperboard cup in accordance with the preferred embodiment of the present invention;

FIG. 2 is a fragment of sectional elevation view of FIG. 1 taken along section line 2-2;

FIG. 3 is top perspective view of a first unitized cut and scored paperboard blank for forming the cup depicted in FIG. 1 in accordance to a first embodiment of the present invention;

FIG. 4A is an exploded sectional view of a second unitized cut and scored paperboard blanks representing a respective graphic layer and an insulative layer having a moisture absorbing layer;

FIG. 4B is a sectional view of the graphic layer and an insulative layer taken along section line 4B-4B;

FIG. 4C is a top perspective view of the second unitized cut and scored paperboard blank formed from the graphic layer and an insulative layer attached to one another;

FIG. 5 is a graph which shows comparison of three different cups with respect to total condensation mass gained at 90 F and 65% RH; and

FIG. 6 is a graph which shows comparison of three different cups with respect to drip mass at 90 F and 65% RH.

DETAILED DESCRIPTION OF THE INVENTION

It is advantageous to define several terms before describing the invention. It should be appreciated that the following definitions are used throughout this application.

Definitions

Where the definition of terms departs from the commonly used meaning of the term, applicant intends to utilize the definitions provides below, unless specifically indicated.

For the purposes of the present invention, “Expanded Poly Styrene (EPS) concern” refers to expanded styrene foam. The National Toxicology Program (NTP), a Division of Health and Human Services issued their 12^(th) Registry on Carcinogens. This report now includes styrene in the list Reasonably Anticipated to be a Human Carcinogen.

For the purposes of the present invention, the term “sheet” refers to webs, strips, films, pages, pieces, segments, etc., which may be continuous in form (e.g., webs) for subsequent subdividing into discrete units, or which may be in the form of discrete units (e.g., pieces).

For the purposes of the present invention, “smooth surface” refers to a surface such as paper, film, or foil which can be printed. Common printing methods include gravure, flexography, and lithography.

For the purposes of the present invention, “minimal dripping of condensation” refers to water droplets which condense on the exterior of the drinking cup and descend to the base of the cup under the influence of gravity.

For the purposes of the present invention, “flexural rigidity” refers to the resistance to deformation of the cup's wall particularly under the influence of gripping pressure from the hand of a user. A common means of measuring flexural rigidity is the Foodservice Packaging Institute cup resistance test method.

For the purposes of the present invention, “high quality graphics” refers to the artwork used in generating an image through industrial printing. Line screens in excess of 100 lines per inch used in halftone image reproduction are common measures of high quality graphics.

For the purposes of the present invention, “industrial composting” refers to compost conditions which reduce packages to decomposition products as described in ASTM D6400 and EN13432. Industrial composting is considered a preferred end of life scenario for package waste disposal and treatment.

For the purposes of the present invention, “Recycling” refers to the reuse of package materials by breaking them down into constituent components. A common recycling method for paper products involves submitting the products to water and agitation to break the fiber structure and releasing the fibers for reuse on a paper machine.

For the purposes of the present invention, “source reduction” refers to using a minimum amount of material to achieve package goals. Often this refers to using plastics of lighter gauge, paper of lower basis weight, and glue of lower application rate than might be initially proposed for package design.

For the purposes of the present invention, “humid environments” refer to the ambient moisture level of the air surrounding a paperboard cup. Moisture vapor in the air is condensed on the drinking cup primarily in response to the temperature change of the moisture in the surrounding air and outer surface of the cup cold beverage.

For the purposes of the present invention, “saturation temperature” refers to a temperature at which a fluid has exchanged all of the heat it can without changing state.

For the purposes of the present invention, “insulative layer” of air laid fibers refers to a layer of cellulose, propylene, or other fibers which is formed into a sheet having a mass density lower than typical paperboard, i.e. less than 11 pounds per 3000 square feet per mil of thickness. The low density of the air laid fibers results in a lower thermal conductivity than a typical paper of equivalent thickness.

For the purposes of the present invention, “insulative-absorbtive” layer refers to an insulative layer which contains fibers which also absorb moisture or water.

For the purposes of the present invention, the term “thermoplastic” refers to the conventional meaning of thermoplastic, i.e., a composition, compound, material, etc., that exhibits the property of a material, such as a high polymer, that softens when exposed to sufficient heat and generally returns to its original condition when cooled to room temperature. Thermoplastics may include, but are not limited to, polyesters (e.g., polyhydroxyalkanoates, polyethyleneterephthalate, etc.), poly(vinylchloride), poly(vinyl acetate), polycarbonates, polymethylmethacrylate, cellulose esters, poly(styrene), poly(ethylene), poly(propylene), cyclic olefin polymers, poly(ethylene oxide), nylons, polyurethanes, protein polymers, etc.

For the purposes of the present invention, the term “polylactic acid or polylactide (PLA)” refers to a renewable, biodegradable, thermoplastic, aliphatic polyester formed from a lactic acid or a source of lactic acid, for example, renewable resources such as corn starch, sugarcane, etc. The term PLA may refer to all stereoisomeric forms of PLA including L- or D-lactides, and racemic mixtures comprising L- and D-lactides. For example, PLA may include D-polylactic acid, L-polylactic acid (also known as PLLA), D,L-polylactic acid, meso-polylactic acid, as well as any combination of D-polylactic acid, L-polylactic acid, D,L-polylactic acid and meso-polylactic acid. PLAs useful herein may have, for example, a number average molecular weight in the range of from about 15,000 and about 300,000. In preparing PLA, bacterial fermentation may be used to produce lactic acid, which may be oligomerized and then catalytically dimerized to provide the monomer for ring-opening polymerization. PLA may be prepared in a high molecular weight form through ring-opening polymerization of the monomer using, for example, a stannous octanoate catalyst, tin (II) chloride, etc.

For the purposes of the present invention, the term “starch-based polymer” refers to a polymer, or combination of polymers, which may be derived from, prepared from, etc., starch. Starch-based polymers which may be used in embodiments of the present invention may include, for example, polylactic acid (PLA), thermoplastic starch (for example, by mixing and heating native or modified starch in the presence of an appropriate high boiling plasticizer, such as glycerin and sorbitol, in a manner such that the starch has little or no crystallinity, a low T_(g), and very low water, e.g., less than about 5% by weight, for example, less than about 1% water), plant starch (e.g., cornstarch), etc., or combinations thereof.

For the purposes of the present invention, the term “cellulose-based polymer” refers to a polymer, or combination of polymers, which may be derived from, prepared from, etc., cellulose. Cellulose-based polymers which may be used in embodiments of the present invention may include, for example, cellulose esters, such as cellulose formate, cellulose acetate, cellulose diacetate, cellulose propionate, cellulose butyrate, cellulose valerate, mixed cellulose esters, etc., and mixtures thereof.

A preferred embodiment of the invention comprises a unitized blank for making a beverage cup having a graphics layer and an insulative layer wrapped around the paperboard cup with a moisture absorbing surface. The combination of wrap (graphics layer and an insulative layer) and cup have a surface rigidity value measurable by the FPI rigidity test method when saturated.

The graphics layer comprises a compostable film or mineral and an insulative layer of 20 to 350 gsm of fibers from the group of cellulose, PLA, bicore PLA-cellulose, starch, and paper.

An alternative embodiment of the present invention comprises a unitized blank for wrapping a beverage cup comprising a graphics layer and an insulative and absorbant layer wrapped on a cup.

The graphics layer comprising a compostable film or mineral and an insulative layer of 20 to 350 gsm of fibers from the group of cellulose, PLA, bicore PLA-cellulose, starch, paper where the absorbent layer has a capacity to absorb condensation.

The graphics layer comprising a printable surface of paper, clay, LDPE, PP, PET or other noncompostable thermoplastic and an insulative layer of 20 to 350 gsm comprising thermoplastic foam, paper, air laid fiber.

DESCRIPTION

FIG. 1 is a perspective view of an open-top paperboard cup 10 in accordance to the preferred embodiment of the present invention. For illustrative purposes, the open-top cup is generally a paperboard cup 10 having a bottom wall 11, a side wall 12 extending upwardly from the bottom wall 11 and an outwardly curled lip 14 formed on the free edge of the side wall 12. The bottom wall 11 is formed preferably from flat, circular sheet of paperboard, which is folded downwardly along periphery and attached to the side wall 12. The paperboard cup 10 could be a beverage cup which the open-top is defined by the rim of the cup. The paperboard cup 10 includes a frusto-conical shape defined by an enclosed bottom 11 and the open-top 13. The outer surface of the side wall 12 of the cup 10 is covered with a respective insulative layer 16 and a graphic layer 18. The insulative layer 16 is sandwiched between the outer surface 12 of the cup and the graphic layer 16 as depicted best in FIG. 2. The insulative layer 16 contains moisture absorbing layer or a moisture absorbing characteristic.

FIG. 3 is top perspective view of a first unitized paperboard blank 20 for forming the side wall 12 of paperboard cup 10 depicted in FIG. 1 in accordance to a first embodiment of the present invention. The unitized blank 20 is substantially flat symmetrical with respect to its lateral axis thereof. The unitized blank 20 is preferably an integral piece of a material such as continuous sheet of conventional paper, paperboard or corrugated paperboard. The unitized blank 20 is cut along its outer margins to form its frusto-conical shape. The unitized blank 20 is formed from three layers namely the side wall layer 12, the insulative layer 16 and the graphic layer 18 which are adhesively or other means such as heat or sonic sealing techniques, attached to one another. The insulative layer 16 contains fibers which also absorb moisture or water and prevent the condensation of water vapor on the outer surface 12 of the cup 10. After forming the unitized blank 20, the cup bottom wall 11 is positioned towards lower end of the side wall 12, which is formed by wrapping the unitized blank 20 around a mandrel and sealing opposing ends to one another, as it is customary in cup-forming techniques. In the preferred embodiment of the invention, to construct the paperboard cup 10, the side walls 12 with the cup bottom wall 11 are first attached to one another on the cup forming machine and in the second step the insulative layer 16 and the graphic layer 18 are adhesively or other means are attached to the side wall 12.

FIGS. 4A, 4B, and 4C are directed to steps of a preferred embodiment that first the insulative layer 16 and the graphic layer 18 are attached to one another to form a second unitized blank 24, which then adhesively or by other means attached to the outer surface of the sidewall 12. The insulative layer 16 of air laid fibers is a layer of cellulose, propylene, or other fibers which is formed into a sheet having a mass density lower than typical paperboard, i.e. less than 11 pounds per 3000 square feet per mil of thickness. The low density of the air laid fibers results in a lower thermal conductivity than a typical paper of equivalent thickness. The graphics layer 18 comprises a compostable film or mineral and an insulative layer of 20 to 350 gsm of fibers from the group of cellulose, PLA, bicore PLA-cellulose, starch, and paper. The graphics layer 18 has a printable surface of paper, clay, LDPE, PP, PET or other noncompostable thermoplastic and an insulative layer of 20 to 350 gsm comprising thermoplastic foam, thermoset foam, paper, and air laid fiber. The unitized blank 24 of preferred embodiment in which the graphic layer 18 is substantially planar and the inner and outer surfaces of the unitized blank 24 have more than one level as a result of skiving, embossing, foaming, pattern printing or other contouring operation.

FIG. 5 is a graph which shows comparison of three different cups with respect to total condensation mass gained at 90 F and 65% RH. It is self-evident that a 16 oz instant invention cup is superior as compared to the prior art 16 oz or prior art 20 oz.

FIG. 6 is a graph which shows comparison of three different cups with respect to drip mass at 90 F and 65% RH. It is self-evident that a 16 oz instant invention cup is superior as compared to the prior art 16 oz or prior art 20 oz.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims. 

1. An open-top cup comprising: a bottom wall, a side wall having inner and outer surfaces extending upwardly from the bottom wall and an outwardly curled lip formed on a free edge of the side wall, an insulative layer having a moisture absorbing characteristic configured to be attached to the outer surface of the side wall coextensively, a graphic layer configured to be attached to the insulative layer coextensively and wherein the open-top cup has at least 25% higher moisture absorbing capability as compared to an open-top cup without having the insulative layer.
 2. The open-top cup of claim 1 wherein the insulative layer is an insulative-absorbtive layer contains fibers which absorb moisture or water.
 3. The open-top cup of claim 1 wherein the insulative layer includes 20 to 350 gsm of fibers from the group of cellulose, PLA, bicore PLA-cellulose, starch, and paper.
 4. The open-top cup of claim 1 wherein the insulative layer of air laid fibers is made of a layer of cellulose, propylene, or other fibers which is formed into a sheet having a mass density lower than typical paperboard.
 5. The open-top cup of claim 4 wherein the lower mass density is less than 11 pounds per 3000 square feet per mil of thickness.
 6. The open-top cup of claim 4 wherein low density of the air laid fibers results in a lower thermal conductivity than a typical paper of equivalent thickness.
 7. The open-top cup of claim 1 wherein the graphics layer comprising a printable surface of paper, clay, LDPE, PP, PET or other noncompostable thermoplastic.
 8. An open-top cup comprising: a bottom wall, a side wall having inner and outer surfaces extending upwardly from the bottom wall and an outwardly curled lip formed on a free edge of the side wall, an insulative layer having a moisture absorbing characteristic configured to be attached to the outer surface of the side wall coextensively wherein the insulative layer includes 20 to 350 gsm of fibers from the group of cellulose, PLA, bicore PLA-cellulose, starch, and paper, a graphic layer configured to be attached to the insulative layer coextensively and wherein the open-top cup has at least 25% higher moisture absorbing capability as compared to an open-top cup without having the insulative layer and wherein the graphics layer comprising a printable surface of paper, clay, LDPE, PP, PET or other noncompostable thermoplastic. 